In liquid processing industry, such as food processing, mixers are widely used for providing an efficient mix of liquids with solid and/or gaseous contents. Within this technical field it is common to divide the available mixers into i) batch mixers or ii) inline mixers. Typically, a batch mixer operates by circulating the media to be mixed within a tank and it is often a preferred choice for high viscous fluids. Inline mixers are typically operating in a different manner, in which the fluids are circulated outside the tank for continuously mixing liquid. As compared with batch mixers, inline mixers are often preferred for low viscous liquids and for large volume production.
The pumping ability of existing in-line mixers and especially existing in-line high-shear mixers is significantly reduced when the liquid viscosity is increased. At viscosities above 1000 cP their pumping ability is often completely lost, in particular if their pump performance is based on the centrifugal principle. Today this limits the use of inline mixers to mixing applications for relatively low viscous fluids.
An example of a food processing mixer is described in WO2009/089837. The mixer includes a tank with a plurality of filling openings and a discharge opening at the bottom of the tank. A high shear rotor mixer is arranged at the bottom of the tank, and is fluidly connected to a valve being capable of diverting mixed liquid either out from the tank or back into the tank. Solid particles to be mixed are introduced in the tank at a level below the current filling level.
Although such mixer is very well functioning and provides numerous advantages, it has been suggested to provide an improved mixer reducing the complexity as well as reducing the risk of having non-dissolved powder lumps present in the liquid.